GigaOm offers and artilce highlighting startups looking at developers, not end-users, as customers. The "new" startups use the API as their stock in trade. The final part of the article is a chart (noted as incomplete) that lists incumbents and disruptors in a variety of areas from e-mail to well, mapping. Here are the companies in the mapping/GIS row.
(incumbents) ESRI, Trimble, MapQuest
|(disruptors) CloudMade, Google Maps|
Are those companies/products arranged correctly? What would you change or add?